Engineering Commons^™

Effect Of Stress Ratio On Fatigue Crack Growth Rate At Notched Hole In 7075-T6 Aluminum Alloy Under Biaxial Fatigue, Reja Alshahrani

Theses and Dissertations

This research investigates the behavior of fatigue crack growth rate in both laboratory air and saltwater (3.5% NaCl) environments for notched cruciform specimen made from 7075-T6 aluminum alloy sheet at different stress ratios. With biaxility ratio of 1, and frequency of applied load of 10 Hz, the crack growth behavior was investigated under in-plane biaxial tension-tension fatigue with 0.1, 0.5, 0.7 stress ratios and then compared them to study the effect of stress ratio on the crack growth rate. Finite Element Analysis (FEA) was used to calculate cyclic variation of stress intensity factors (delta K) at the crack tips. The …

Adaptive Estimation And Heuristic Optimization Of Nonlinear Spacecraft Attitude Dynamics, Joshuah A. Hess

Theses and Dissertations

For spacecraft conducting on-orbit operations, changes to the structure of the spacecraft are not uncommon. These planned or unanticipated changes in inertia properties couple with the spacecraft's attitude dynamics and typically require estimation. For systems with time-varying inertia parameters, multiple model adaptive estimation (MMAE) routines can be utilized for parameter and state estimates. MMAE algorithms involve constructing a bank of recursive estimators, each assuming a different hypothesis for the systems dynamics. This research has three distinct, but related, contributions to satellite attitude dynamics and estimation. In the first part of this research, MMAE routines employing parallel banks of unscented attitude …

Orbit Determination Using Vinti's Solution, Steven P. Wright

Theses and Dissertations

Orbital altitudes congested with spacecraft and debris combined with recent collisions have all but negated the Big Sky Theory. As the sheer number of orbital objects to track grows unbounded so does interest in prediction methods that are rapid and minimally computational. Claimed as the \other solvable solution, the recently completed solution too orbital motion about the earth, based on Vinti's method and including the major effects of the equatorial bulge, opens up the prospect of much more accurate analytical models for space situational awareness. A preliminary examination of this solution is presented. A numerical state transition matrix is found …

An Examination Of Commercial Motor Vehicle Hours Of Service Safety Regulation, Jason R. Anderson

Theses and Dissertations

The Federal Motor Carrier Safety Administration (FMSCA) stipulates Hours of Service (HOS) regulations in order to minimize or eliminate fatigued truck driving, a major cause of truck-related accidents. This research examines the efficacy of HOS with three unique research approaches: 1) a typology classification model to indicate differences in HOS regulation from other safety regulations, 2) an exhaustive enumeration method utilizing the theoretical foundation of perishable inventory theory, and 3) a statistical analysis on accidents caused by or involving truck drivers. This research provides insight into similar Air Force Instructions regarding flight-time restrictions for pilots, which attempt to prevent flying …

Application Of Executable Architecture In Early Concept Evaluation Using The Dod Architecture Framework, Zhongwang Chua

Theses and Dissertations

The increasing complexity in the development of today's modern warfighting systems demands a systematic evaluation approach in the assessment of the envisaged capability and estimating the cost effectiveness, especially in the early stages of Concept Development. This research focused on the development of early Concept evaluation methodology through the use of Executable Architecture (EA) through the System Architecting process. Particularly, the methodology was applied in the assessment of a proposed Multi-tiered Unmanned Aircraft System System-of-System that is designed provide target acquisition and conduct dynamic strike on Theater Ballistic Missile launchers. Through the implementation of the evaluation methodology using dynamic modeling …

Evaluation Of The Impact Of An Additive Manufacturing Enhanced Cubesat Architecture On The Cubesat Development Process, Rachel E. Sharples

Theses and Dissertations

Additive manufacturing (AM) is a fabrication method ideally suited to low-quantity, highly customized builds, leading to interest in its application to satellite development and manufacturing, where each build is unique. Due to the issues of long development schedules and high development and manufacturing costs, methods are needed in the CubeSat development process to reduce the weight and volume of subsystems and decrease integration time. The work develops an architecture for an AM-augmented CubeSat and examines the AM techniques of embedded electronics, embedded thrusters, and custom radiation-hardened materials can impact the subsystems of a CubeSat. The AM-augmented architecture shows a shift …

Cavity Geometric Features And Entrainment Characterization Resulting From A Ballistically Induced Hydrodynamic Ram Event, Andrew J. Lingenfelter

Theses and Dissertations

Hydrodynamic Ram can cause damage to industrial and aircraft systems. The resulting transient spray increases the probability of fire. To better understand the driving mechanisms behind transient spray, internal, and external measurements of the cavity geometry, and entrained flow field were accomplished. Research determined cavity contraction and separation are pre-cursors to the initiation of the transient spray phases. The entrained flow measurement required development of a new and novel technique using a continuous wave laser and atomized water particles. The peak mass flow correlated well with cavity geometric features, such as cavity contraction. Using the mass flow, cavity diameter at …

The Impact Of Satellite Sensor Viewing Geometry On Time-Series Analysis Of Volcanic Emissions, Verity Flower, Simon A. Carn, Robert Wright

Michigan Tech Publications, Part 1

Time-series analysis techniques are being increasingly used to process satellite observations of volcanic gas emissions and heat flux, with the aim of identifying cyclic behaviour that could inform hazard assessment or elucidate volcanic processes. However, it can be difficult to distinguish cyclic variations due to geophysical processes from those that are artefacts of the observation technique. Here, we conduct a comprehensive investigation into the origin of cyclicity in volcanic observations by analysing daily, global satellite measurements of volcanic SO2 loading by the Ozone Monitoring Instrument (OMI) and thermal infrared anomalies detected by the Moderate Resolution Imaging Spectroradiometer (MODIS). We use …

A Global Catalogue Of Large So < Inf> 2 Sources And Emissions Derived From The Ozone Monitoring Instrument, Vitali E. Fioletov, Chris A. Mclinden, Nickolay Krotkov, Can Li, Joanna Joiner, Nicolas Theys, S. Carn, Mike D. Moran

Michigan Tech Publications, Part 1

Sulfur dioxide (SO2) measurements from the Ozone Monitoring Instrument (OMI) satellite sensor processed with the new principal component analysis (PCA) algorithm were used to detect large point emission sources or clusters of sources. The total of 491 continuously emitting point sources releasing from about 30 kt yr-1 to more than 4000 kt yr-1 of SO2 per year have been identified and grouped by country and by primary source origin: volcanoes (76 sources); power plants (297); smelters (53); and sources related to the oil and gas industry (65). The sources were identified using different methods, including through OMI measurements themselves applied …

Compositionally Graded Bulk Heterojunction Devices And Methods Of Manufacturing The Same, Jinsong Huang, Zhengguo Xiao

Department of Mechanical and Materials Engineering: Faculty Publications

Systems and methods are described to form compositionally graded BHJ structures utilizing solvent-fluxing techniques. In implementations, the systems and methods described herein involve a high boiling point additive, a solution of a polymer donor and an acceptor, a substrate material, a working solvent, and a flux solvent for formation of compositionally graded BHJ structures.

Improving Real-World Performance Of Vision Aided Navigation In A Flight Environment, Donald T. Venable

Theses and Dissertations

The motivation of this research is to fuse information from an airborne imaging sensor with information extracted from satellite imagery in order to provide accurate position when GPS is unavailable for an extended duration. A corpus of existing geo-referenced satellite imagery is used to create a key point database. A novel algorithm for recovering coarse pose using by comparing key points extracted from the airborne imagery to the reference database is developed. This coarse position is used to bootstrap a local-area geo-registration algorithm, which provides GPS-level position estimates. This research derives optimizations for existing local-area methods for operation in flight …

Technology-Assisted Stroke Rehabilitation In Mexico: A Pilot Randomized Trial Comparing Traditional Therapy To Circuit Training In A Robot/Technology-Assisted Therapy Gym, Karla Bustamante Valles, Sandra Montes, Maria De Jesus Madrigal, Adan Burciaga, María Elena Martínez, Michelle J. Johnson

Biomedical Engineering Faculty Research and Publications

Background

Stroke rehabilitation in low- and middle-income countries, such as Mexico, is often hampered by lack of clinical resources and funding. To provide a cost-effective solution for comprehensive post-stroke rehabilitation that can alleviate the need for one-on-one physical or occupational therapy, in lower and upper extremities, we proposed and implemented a technology-assisted rehabilitation gymnasium in Chihuahua, Mexico. The Gymnasium for Robotic Rehabilitation (Robot Gym) consisted of low- and high-tech systems for upper and lower limb rehabilitation. Our hypothesis is that the Robot Gym can provide a cost- and labor-efficient alternative for post-stroke rehabilitation, while being more or as effective as …

Applying Lean To The Ac-130 Maintenance Process For The Royal Saudi Air Force, Fisal A. Alzahrani

Theses and Dissertations

The ideas expressed in this research come from the researchers experiences working in the AC-130 maintenance squadron in the Royal Saudi Air Force. The AC-130 maintenance process is not currently being used as effectively as it could be to make AC-130 fully mission capable. That can be done by improving communication, reducing distances needed to move or transport anything during the maintenance process and by efficient use of the available qualified workforces, tools and equipment. Consideration is given to applying an existing management technique to the Royal Saudi Air Forces AC-130 Maintenance Squadrons. The selected technique is the Lean management …

Optimal Control Of An Uninhabited Loyal Wingman, Clay J. Humphreys

Theses and Dissertations

As researchers strive to achieve autonomy in systems, many believe the goal is not that machines should attain full autonomy, but rather to obtain the right level of autonomy for an appropriate man-machine interaction. A common phrase for this interaction is manned-unmanned teaming (MUM-T), a subset of which, for unmanned aerial vehicles, is the concept of the loyal wingman. This work demonstrates the use of optimal control and stochastic estimation techniques as an autonomous near real-time dynamic route planner for the DoD concept of the loyal wingman. First, the optimal control problem is formulated for a static threat environment and …

Physical Layer Defenses Against Primary User Emulation Attacks, Joan A. Betances

Theses and Dissertations

Cognitive Radio (CR) is a promising technology that works by detecting unused parts of the spectrum and automatically reconfiguring the communication system's parameters in order to operate in the available communication channels while minimizing interference. CR enables efficient use of the Radio Frequency (RF) spectrum by generating waveforms that can coexist with existing users in licensed spectrum bands. Spectrum sensing is one of the most important components of CR systems because it provides awareness of its operating environment, as well as detecting the presence of primary (licensed) users of the spectrum.

The Scaling Of Loss Pathways And Heat Transfer In Small Scale Internal Combustion Engines, Joseph K. Ausserer

Theses and Dissertations

Prior literature indicates fuel conversion efficiency and normalized power deteriorate increasingly rapidly with decreasing displacement, but does not fully reveal the driving losses. The literature also suggested that increasing losses relax the required fuel anti-knock index (AKI), but offered conflicting conclusions on the performance impact. This comprehensive experimental study of three, 28 cm3 to 85 cm3 displacement, commercial-off-the-shelf (COTS), two-stroke ICEs identified short-circuiting as having the most deleterious impact on COTS engine performance in this size range. Heat transfer losses were comparable to larger engines for displaced volumes greater than 10 cm3. An engine friction model was developed that uses …

Air Force Project Risk Management – The Impact Of Inconsistent Processes, Eric J. Perez

Theses and Dissertations

On the surface, the majority of Air Force units appear to be executing some form of project risk management (PRM). Deeper investigation exposes many of the PRM practices currently in place to often be ad hoc, and as such, have the potential to poorly inform decisions when risk data is escalated to the enterprise levels of the Air Force. Resultantly, there is inconsistency between the PRM processes practiced by Air Force units. This inconsistency is an indication of risk mishandling at the project level and erroneous risk data provided at the enterprise levels of the Air Force. It may be …

Corrosion Fatigue Crack Growth Behavior At Notched Hole In 7075-T6 Under Different Biaxial Stress Ratios, Khalid A. Alghamdi

Theses and Dissertations

This thesis presents the results of a study to quantify the effects of biaxial loading on fatigue crack behavior in both air and saltwater (3.5% NaCl) environments from pre-cracked notched circular hole in a 7075-T6 cruciform specimen using a fracture mechanics approach. With stress ratio of R = 0.5, the crack growth behavior was investigated under fatigue loading with 0.5, 0, -0.5, and -1 biaxial stress ratio lambda. The crack propagation was monitored using optical microscopy. Finite Element Analysis was performed using the different stress ranges and stress ratios with various crack sizes to compute of stress intensity factors (delta …

Mechanical Properties And Fatigue Behavior Of Unitized Composite Airframe Structures At Elevated Temperature, Mohamed Noomen

Theses and Dissertations

The tension-tension fatigue behavior of a newly developed unitized composite material system was investigated. The unitized composite consisted of a polymer matrix composite (PMC) co-cured with a ceramic matrix composite (CMC). The PMC portion consisted of an NRPE high-temperature polyimide matrix reinforced with carbon fibers woven in an eight harness satin weave (8HSW). The CMC layer is a single-ply non-crimp 3D orthogonal weave composite consisting of ceramic matrix reinforced with glass fibers. In order to assess the performance and suitability of this composite for use in aerospace components designed to contain high-temperature environments, mechanical tests were performed under temperature conditions …

Mechanical Design And Optimization Of An Interactive Animatronic Bald Eagle, Eric Burns

Phi Kappa Phi Research Symposium (Archived)

Animatronics is a specialized sub-category of mechatronics, a fusion of mechanical and electrical engineering. The field has grown from small, individual projects into a major industry. As animatronics progress, mechanical engineers are pushed to design internal structures which occupy ever-decreasing spaces and to ensure designs can undergo maintenance and modifications smoothly. This research investigates methods of reducing space required for mechanisms and several other beneficial methods of development as well as varying satisfactions for audiences when exposed to actor-controlled systems rather than pre-scripted functions. The mechanical systems are designed using CAD software available at Georgia Southern. On-campus, resources are used …

Systematic Identification Of Coordination Gaps In Pediatric Care, Diana M. Prieto, Anil Kumar, Catherine L. Kothari, Cheryl Dickson

Frontiers in Public Health Services and Systems Research

In the United States, the status of coordination among pediatric care services is not well understood. Through the use of quality improvement (QI) techniques, coordination gaps were systematically identified in the interagency network of pediatric services in Kalamazoo MI. Gaps were found in transportation resources, follow-up procedures, awareness of services, interagency communication, insurance limitations, population behaviors, and resource utilization. This preliminary study reveals the need for (1) protocols for intra- and inter-agency communication, (2) mechanisms for easy and fast retrieval of pediatric resources, and (3) health information exchange.

Nonlinear Machine Learning And Design Of Reconfigurable Digital Colloids, Andrew W. Long, Carolyn L. Phillips, Eric Jankowski, Andrew L. Ferguson

Materials Science and Engineering Faculty Publications and Presentations

Digital colloids, a cluster of freely rotating “halo" particles tethered to the surface of a central particle, were recently proposed as ultra-high density memory elements for information storage. Rational design of these digital colloids for memory storage applications requires a quantitative understanding of the thermodynamic and kinetic stability of the configurational states within which information is stored. We apply nonlinear machine learning to Brownian dynamics simulations of these digital colloids to extract the low-dimensional intrinsic manifold governing digital colloid morphology, thermodynamics, and kinetics. By modulating the relative size ratio between halo particles and central particles, we investigate the size-dependent configurational …

From Xst To F-117a, Alan Brown

ERAU Prescott Aviation History Program

Learn the remarkable story of stealth technology from the man often referred to as “Mr. Stealth.” From 1975-1989 Alan Brown was a member of Lockheed “Skunk Works”, becoming program manager & chief engineer for the F-117A Stealth Fighter from initial concept until the first production aircraft was built, 1978 to 1982. Hear the inside story of the many challenges faced by the stealth program and how they were solved.

An Exploration Of Wind Stress Calculation Techniques In Hurricane Storm Surge Modeling, Kyra M. Bryant, Muhammad Akbar

Mechanical and Manufacturing Engineering Faculty Research

As hurricanes continue to threaten coastal communities, accurate storm surge forecasting remains a global priority. Achieving a reliable storm surge prediction necessitates accurate hurricane intensity and wind field information. The wind field must be converted to wind stress, which represents the air-sea momentum flux component required in storm surge and other oceanic models. This conversion requires a multiplicative drag coefficient for the air density and wind speed to represent the air-sea momentum exchange at a given location. Air density is a known parameter and wind speed is a forecasted variable, whereas the drag coefficient is calculated using an empirical correlation. …

Organic Resin Laminate, Methods Of Making And Ssing The Same, And Articles Comprising The Same, Mary Gilliam, Koichi Higuchi

Chemical Engineering Patents

An organic resin laminate comprising an organic resin substrate and a multilayer coating system thereon has weather resistance and mar resistance. The multilayer coating system includes an outermost layer (I) which is a hard film resulting from plasma polymerization of an organosilicon compound and an intermediate layer (II) which is a cured film of a composite coating composition (2) comprising inorganic oxide nanoparticle and vinyl copolymer.

Carbon Particles, Stephen M. Lipka, Christopher R. Swartz

Center for Applied Energy Research Faculty Patents

A composition generally includes carbon particles. The particles are prepared by dissolving a carbohydrate-based precursor in water to form a precursor solution and placing the precursor solution in a pressure vessel. The precursor solution is placed in a pressure vessel. The pressure vessel is heated to a reaction temperature to form carbon particles. The carbon particles are subjected to a chemical activation and a physical activation. The composition includes, by weight, about 5% to about 30% oxygen.

High-Performance And Flexible Thermoelectric Films By Screen Printing Solution-Processed Nanoplate Crystals, Tony Varghese, Courtney Hollar, Joseph Richardson, Nicholas Kempf, Chao Han, Pasindu Gamarachchi, David Estrada, Yanliang Zhang

Materials Science and Engineering Faculty Publications and Presentations

Screen printing allows for direct conversion of thermoelectric nanocrystals into flexible energy harvesters and coolers. However, obtaining flexible thermoelectric materials with high figure of merit ZT through printing is an exacting challenge due to the difficulties to synthesize high-performance thermoelectric inks and the poor density and electrical conductivity of the printed films. Here, we demonstrate high-performance flexible films and devices by screen printing bismuth telluride based nanocrystal inks synthesized using a microwave-stimulated wet-chemical method. Thermoelectric films of several tens of microns thickness were screen printed onto a flexible polyimide substrate followed by cold compaction and sintering. The n-type films demonstrate …

Linder, Gary (Fa 953), Manuscripts & Folklife Archives

Folklife Archives Finding Aids

Finding aid only for Folklife Archives Project 953. Paper titled: “White Mills.” Project includes a description and photo of White Mills village and the watermill in Hardin County, Kentucky.

Form, Function Or Fiction: Gender And Diversity In Engineering Programmes In Ireland, Domhnall Sheridan, Una Beagon, Eabhnat Ni Fhloinn

Conference papers

Messe agus Pangur Bán, cechtar nathar fria shaindán: bíth a menmasam fri seilgg, mu menma céin im shaincheirdd.

I and Pangur Bán, my cat 'Tis a like task we are at; Hunting mice is his delight Hunting words I sit all night.

The poem Pangur Bán [1] was written by an unknown Irish monk in the Benedictine Abbey of Reichenau, in southern Germany in the ninth century. The Abbey, founded in 724 by Saint Pirim, was a centre of learning in Europe for many centuries, reaching its apex under Abbot Berno of Reichenau (1008–48). The Christian church was the sole …

Seeing The Threat: Pilot Visual Detection Of Small Unmanned Aircraft Systems In Visual Meteorological Conditions, Jon M. Loffi, Ryan J. Wallace, Jamey D. Jacob, Jared C. Dunlap

International Journal of Aviation, Aeronautics, and Aerospace

One key challenge of integrating Unmanned Aircraft Systems (UAS) platforms into the National Airspace System (NAS) is the potential for midair collisions between manned aircraft and the unmanned system. The lack of an established UAS benchmark for Detect, Sense & Avoid Systems put the preponderance of avoidance efforts on manned aircraft pilots to visually see and avoid potential collision threats. The small size, unusual configurations, and diverse operational applications of unmanned systems make UAS platforms difficult to visually identify. This paper sought to determine the mean visibility distance of small UAS systems (sUAS) to an alerted pilot flying a general …